Gliederung

Objective: To demonstrate our technique of dealing with the intradural and laterally extended tumor compartments during the endoscopic endonasal removal of midline skull base tumours.

Methods: In a consecutive series of 91 midline skull base tumors (81 pituitary lesions, 8 chordomas / chondrosarcoma, 2 meningiomas) operated through the endoscopic endonasal approach, 15 demonstrated intradural and 32 lateral tumor extension including pituitary tumor with the Knosp grading of 3 and 4. The hybrid integrated endoscope-holder system was used (EndoArm, Olympus Co.). The system enabled instant fixation and release of the endoscope allowing bimanual surgery performed by a single surgeon. Basically, the binostril transseptal approach was employed. For the intradural compartment, the performance of meticulous surgical maneuvers analogous to those under the open microsurgery was intended. For the lateral tumor compartment, specially designed malleable / steerable instruments were used to remove the tumor behind the vital structures under the side-viewing endoscope.

Results: By dealing with the intradural compartment, maintenance of the membranous structure was the key to safe and sufficient tumor removal, and dense adhesion and egg-shell like calcification were the factors adversely affecting the result. Removal of the lateral compartment under the side-viewing endoscope was especially efficient for the intrasellar and extradural retro-carotid space. In the intradural space, however, the surgical maneuver was mostly restricted to blunt dissection and simple suctioning due to the lack of fine dissection and cutting surgical instruments.

Conclusions: The management of midline skull base tumor was improved by performing surgical maneuvers analogous to those under the open microsurgery and with the application of specially designed malleable / steerable instruments. The armamentarium of the surgical instruments, however, is still not satisfactory and its further development would be an urgent requirement.